BACKGROUND OF THE INVENTION
The present invention relates to a floor lock system for a surgery table and, more particularly, to a floor lock system for supporting a surgery table on an uneven floor surface.
Surgery tables are typically formed as portable units supported on casters whereby the table may be transported between rooms of a hospital and/or moved to desired orientations within an operating room. Once the surgery table is located at a desired position, floor locks may be engaged to positively lock the table in its desired position to thereby prevent movement of the table during an operation. For example, vertically moveable legs may be provided at each of four corners of the table wherein the legs, are moved downwardly into engagement with the floor. Upon engaging the floor, the legs cause the surgery table to move upwardly such that the table is supported by the legs.
One problem associated with the above-described floor lock system wherein vertically moveable legs are provided occurs when the floor surface is irregular or uneven such that the table is permitted to wobble slightly due to at least one of the legs being located in spaced relation to the floor surface when the other three legs are engaged with the floor. For example, floor irregularities may be on the order of one-quarter inch. In order to compensate for irregularities in the floor surface, one of the vertically moveable legs may be provided with an adjustable floor engaging portion wherein the adjustable floor engaging portion may be manually screwed in or out of the vertically moveable leg in order to adjust the length of the leg. This solution has proven to be inconvenient in that if it is desired to move the surgery table, it is either necessary to mark the locations for positioning the support legs or adjust the legs each time the table is moved.
Further, such a support system may permit a small amount of wobbling during a surgical operation. During certain delicate operations, such as microsurgery operations, even small movements of the table are undesirable.
Accordingly, there is a need for a floor lock system for use with a surgery table wherein the system is capable of automatically compensating for any irregularities in a floor surface.
SUMMARY OF THE INVENTION
The present invention provides a floor lock system for use with a surgery table wherein the floor lock system adjusts for irregularities in floor surfaces to thereby provide a stable support for the table.
In one aspect of the invention, a floor lock system is provided for supporting a base member of a surgery table on a floor surface the system including primary lock members supported on the base member and actuated by a first actuator for causing the primary lock members to engage the floor surface. At least one secondary lock member is provided supported on the base member and actuated by a second actuator for causing the secondary lock member to engage the floor surface. The first actuator is adapted to apply a greater force to the primary lock members than a force applied by the second actuator to the secondary lock member.
In a further aspect of the invention, the surgery table supported by the floor lock system includes a patient support surface supported by the base member and defining a longitudinal axis. First and second ones of the primary lock members are located on laterally opposite sides of the longitudinal axis adjacent to a head end of the table and a third primary lock member is located adjacent to a foot end of the table generally aligned along the longitudinal axis. First and second secondary lock members are located on laterally opposite sides of the longitudinal axis adjacent to the third primary lock member.
In operating the floor lock system of the present invention, the primary lock members are initially moved into engagement with the floor surface and extended to a predetermined position lifting the surgery table from the floor surface. Subsequently, the secondary lock members are actuated to move into engagement with the floor surface. The secondary lock members move an indeterminate distance until they contact the floor surface. The mechanism for actuating the secondary lock members applies a lesser force than the mechanism for actuating the primary lock members such that the secondary lock members do not provide a lift force to the surgery table but provide an anti-tilt function while compensating for irregularities in the floor surface. The primary and secondary lock members preferably comprise legs actuated for vertical movement by first and second cylinders forming the first and second actuators.
Therefore, it is an object of the present invention to provide a floor lock system for use with a surgery table wherein lock members are actuated to automatically compensate for irregularities in a floor surface.
It is a further object of the invention to provide such a floor lock system wherein a first set of lock members are provided for lifting the table and a second set of lock members compensate for irregularities in the floor surface and provide an anti-tilt function for the table.
It is yet another object of the invention to provide such a floor lock system wherein manual adjustment of the lock members is not required to obtain proper adjustment for uneven or irregular floor surfaces.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a surgery table incorporating the floor lock system of the present invention;
FIG. 2 is a bottom plan view of the surgery table of FIG. 1;
FIG. 3 is a front elevational view of the base portion of the surgery table of FIG. 1 wherein the base is partially cut away; and
FIG. 4 is a diagrammatic view of a fluid system for controlling the cylinder actuators for the floor locks.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, the floor lock system of the present invention is adapted to be used in combination with a surgery table 10 having a
base 12, a support column 14 extending upwardly from an end of the
base 12, and a
table top 16 supported at the top of the column 14. It should be noted that the table top extends in cantilever manner from a
head end 18 of the table 10 toward a
foot end 20 thereof. Further, the
base 12 includes a
head end portion 22 adjacent to the column 14 and a
foot end portion 24 located distal from the column 14.
Referring to FIG. 2, the table 10 is further provided with
rear casters 26 and
front casters 28 which are freely movable to guide the table 10 in rolling movement across a floor surface.
Referring to FIGS. 1 and 2, the floor lock system of the present invention includes primary lock members comprising first and second
primary lock members 30 and 32 adjacent to the
head end portion 22 and a third
primary lock member 34 adjacent to the
foot end portion 24. The third
primary lock member 34 is located generally along a
longitudinal axis 36 defined by the
base member 12, which longitudinal axis corresponds to a longitudinal axis for the table 10. The
primary lock members 30, 32, 34 are actuated for movement by an actuator or actuator system comprising respective fluid actuated
cylinders 38, 40, 42 for moving legs or
floor engaging members 44 into engagement with a floor surface 70 (see also FIGS. 3 and 4). The first and second
primary lock members 30, 32 are located substantially equidistant from the
third lock member 34 and a
primary tip line 46 is defined extending between the first and third
primary lock members 30 and 34. Another
primary tip line 48 is defined extending between the second and third
primary lock members 32 and 34. The
primary tip lines 46 and 48 define the sides of a triangle wherein the center of
gravity 50 for the table is located within the triangular area circumscribed by the
primary lock members 30, 32, 34.
It should be noted that under normal circumstances, when a patient is positioned on the
table top 16, the resulting center of gravity will lie within the
triangular area 52. However, under certain circumstances the center of gravity may shift outside of the
triangular area 52 such that a tipping force applied laterally outside of either the
line 46 or
line 48 will be applied to the table 10 causing the table 10 to have a tendency to tip. For example, when a patient is positioned in a reverse position on the table the center of gravity may shift to a point such as the location identified as 54 in FIG. 2. In this instance, the center of gravity at 54 is relatively close to the sides of the
triangle 52 defined by the
lines 46 and 48 such that any forces applied adjacent to the
foot end 20 of the table 10 will likely result in a tipping force being applied to the table 10. Such a reversal of the patient on a surgery table and the associated reconfiguration of the table which may cause such a shift in the center of gravity toward the foot end of the table is described further in U.S. Application Serial No. (attorney Docket MID 171P2), assigned to the assignee of the present invention and incorporated herein by reference.
Referring to FIGS. 1 and 2, in order to further stabilize the table, first and second
secondary lock members 56 and 58 are provided located on laterally opposite sides of the
longitudinal axis 36 at the
head end 24 adjacent to the third
primary lock member 34. The
secondary lock members 56, 58 include a second actuator or actuator system comprising
second actuation cylinders 60 and 62 for moving legs or
floor engaging members 64 into engagement with a floor surface.
As seen in FIG. 2, a
secondary tip line 66 is defined between the first
primary lock member 30 and the first
secondary lock member 56, and another
secondary tip line 68 is defined between the second
primary lock member 32 and the second
secondary lock member 58. The
secondary tip lines 66 and 68 are located laterally outwardly from the location of the
primary tip lines 46 and 48 such that a relatively larger force must be applied to the table 10 in order to cause it to tip. Further, a greater proportion of the patient's weight will be located within the area defined between the
lines 66 and 68 such that a greater restoring force resisting tipping is provided to the table when the
secondary lock members 56 and 58 are engaged with the
floor surface 70.
Referring to FIGS. 3 and 4, it should be noted that the
actuation cylinders 38, 40, 42 for the primary lock members are adapted to apply a greater force than the force applied by the
cylinders 60 and 62 of the secondary lock members. The
cylinders 38, 40, 42 apply a sufficiently large force to fully extend and lift the
casters 26 and 28 clear of the
floor surface 70. Thus, the
floor engaging members 44 define a plane for supporting the table 10. Subsequent to the primary
floor engaging members 44 engaging the
floor surface 70, the secondary
floor engaging members 64 move downwardly into engagement with the
floor surface 70, as depicted in dotted lines in FIG. 3. The combined force applied by the
secondary cylinders 60 and 62 to the
floor engaging members 64 is insufficient to lift the table upon engaging the
floor surface 70. Thus, as the
floor engaging members 64 move into engagement with the
floor surface 70 the table remains supported within the plane defined by the primary
floor engaging members 44, and the secondary
floor engaging members 64 merely provide a force counteracting tipping of the table by moving the tip lines for the table laterally outwardly. Further, it should be noted that as a result of the
cylinders 60 and 62 not providing a force sufficient to lift the table, the movement of the
floor engaging members 64 will terminate upon engagement with the
floor surface 70 such that they will automatically compensate for any irregularities in the floor surface, and may be located in perpendicular spaced relation to the plane defined by the
engaging members 44, while providing a wobble-free stable support for the table 10.
Referring to FIG. 4, a hydraulic circuit for actuating the floor lock system of the present invention is illustrated diagrammatically and is shown as part of a hydraulic system for actuating different articulated portions of the surgery table 10. The hydraulic system includes a pump system 72 defining a pressurized fluid source having an
output line 74 and a
return line 76 wherein the output and
return lines 74, 76 are connected to a plurality of actuators 78 through
control valves 80 for controlling articulated sections of the table 10. The details of the pump system 72, actuators 78 and
control valves 80 are described further in the above referenced U.S. Patent Application No. (Attorney Docket No. MID 171 P2).
During operation of the floor lock system, the controller 82 will initially energize the
first control valve 88 such that a
spool 92 of the
valve 88 shifts to the right for a predetermined time period causing pressurized fluid to flow to the
primary lock members 30, 32, 34. During the predetermined time period, the
floor engaging members 44 will extend outwardly to the full extent of their travel to engage the floor with sufficient force to lift the
casters 26, 28 of the surgery table 10 out of contact with the floor. Subsequently, the
spool 92 will move to a neutral position and a check valve 94 will maintain the fluid pressure to the
primary lock members 30, 32, 34.
The controller 82 will then actuate the
second control valve 90 such that a
spool 96 of the
second control valve 90 moves to the right, resulting in pressurized fluid being supplied to the
secondary lock members 56, 58. The fluid pressure supplied to the
second actuation cylinders 60, 62 is limited to a predetermined pressure, such as 20 bar, by a
pressure relief valve 98 whereby the fluid pressure supplied to the
second actuation cylinders 60, 62 will be less than the fluid pressure supplied to the
first actuation cylinders 38, 40, 42. Further, the
relief valve 98 ensures that the fluid pressure supplied to the
second actuation cylinders 60, 62 is less than the force necessary to provide an additional lifting force to the table 10.
After the pressurized fluid has teen supplied to the
secondary lock members 56, 58 for a predetermined time period, the
spool 96 for the
second control valve 90 is de-energized such that it moves back to a neutral position and a pair of check valves 100 maintain the predetermined pressure within the
second actuation cylinders 60, 62. It should be noted that the
floor engaging members 64 for the
secondary lock members 56, 58 will only extend to the extent that they contact the floor, at which time the pressure within the cylinders will increase to a point where the
pressure relief valve 98 opens to maintain the predetermined pressure to the
second actuation cylinders 60, 62. Thus, although the
secondary lock members 56, 58 do not provide a lifting force to the table 10, the
cylinders 60, 62 are provided with a sufficient force to resist movement when a tipping force is applied to the table 10.
When it is desired to release the floor lock system to lower the
casters 26, 28 back into contact with the floor, the
spool 92 of the
first control valve 88 is caused to shift to the left thereby actuating the check valves 94, 100 to release fluid pressure to the
return line 76. In response thereto, the
floor engaging members 44 and 64 will move into their
respective cylinders 38, 40, 42 and 60, 62 to lower the table 10.
From the above description, it should be apparent that the secondary lock members are adapted to move to an indeterminate position, as determined by irregularities in a floor surface, relative to the plane defined by the primary lock members whereby a highly stable support is provided for the surgery table for avoiding both tipping and wobbling of the table.
While the method herein described, and the form of apparatus for carrying this method into effect, constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise method and form of apparatus, and that changes may be made in either without departing from the scope of the invention, which is defined in the appended claims.